(Corrects name of firm in paragraph 5 of Sept 12 story to CITIC Private Equity Funds Management Co Ltd from CITIC Capital)

Sept 12 (Reuters) - China-based biotechnology firm 3SBio Inc SSRX.O said an investor group led by its chief executive Jing Lou has offered to take the company private for up to $15 per American Depositary Share (ADS), or about $331 million.

The offer, which was made by Lou and the China-focused private equity fund CPEChinaFund LP, represents a 29 percent premium over the $11.59 that the company’s ADS closed at on Tuesday.

Each ADS represents seven ordinary shares of the company, making the offer value for each ordinary share about $2.14. The company had 154.5 million shares outstanding as of Dec. 31, 2011 according to a regulatory filing.

3SBio, which develops and manufactures drugs to treat cancer, kidney diseases, inflammation and infectious diseases, has five products on the market, sold primarily in China.

Lou and CPEChinaFund, an affiliate of Chinese private equity firm CITIC Private Equity Funds Management Co Ltd, will finance the deal through a combination of debt and equity.

They are currently in discussion with a financial institution that is interested in financing the deal, Lou and the private equity fund said in a proposal letter to the company.

3SBio’s board said it has not made any decision regarding the proposal.

The company’s shares, which have risen about 13 percent this year, w ere up about 16 percent at $13.43 in morning trade on the Nasdaq. (Reporting by Esha Dey and Vrinda Manocha in Bangalore; Editing by Supriya Kurane) (Reporting by Saumyadeb Chakrabarty)